Problem: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Daniel needs to master at least $91$ songs. Daniel has already mastered $45$ songs. If Daniel can master $9$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
Answer: To solve this, let's set up an expression to show how many songs Daniel will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Daniel Needs to have at least $91$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 91$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 91$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 9 + 45 \geq 91$ $ x \cdot 9 \geq 91 - 45 $ $ x \cdot 9 \geq 46 $ $x \geq \dfrac{46}{9} \approx 5.11$ Since we only care about whole months that Daniel has spent working, we round $5.11$ up to $6$ Daniel must work for at least 6 months.